module_name_repetitions: don't warn if the item is in a private module.
Fixes <https://github.com/rust-lang/rust-clippy/issues/8524>.
There is still a warning (as there should be) if the item is reexported
by name, but not by glob; that would require further work to examine the
names in the glob, and I haven't looked into that.
Credit to @Centri3 for suggesting approximately this simple fix in
<https://github.com/rust-lang/rust-clippy/issues/8524#issuecomment-1729036149>.
However, per later comment <https://github.com/rust-lang/rust-clippy/issues/8524#issuecomment-2035836495>,
I am not making it configuration-dependent, but *always* checking public
items in public modules only.
a235cbd8ac